2-dimensional effective stress analysis for a damaged bridge located in the caldera of Mount Aso in 2016 Kumamoto earthquake

<p>In this paper, we conducted a two-dimensional effective stress analysis in consideration of the interaction between the ground and the structure for the Kurumakaeri Bridge which is located in the caldera of Mount Aso. From the results of the analyses, it is confirmed that the ground around the abutment subsided by about 26 cm due to the deformation of the soft volcanic ash soil. Furthermore, it is confirmed that the collision between the superstructure and the abutment happened because the abutment moved to the front side. Due to this movement, the deformation of about 34 cm occurred at the rubber bearing after the earthquake ended.</p>

Surface Ground Movement Around a Steel Pipe Pile Foundation During Liquefaction Measured by Effective Stress Analysis

Several studies on liquefaction using physical model tests and numerical analysis have been conducted in recent years; however, few studies have investigated the effect of liquefaction-induced settlement on structures. Especially, this settlement seriously influences on gravity foundation during earthquake. This study aims to investigate the settlement of the surrounding ground of steel pipe sheet pile (SPSP) foundation during liquefaction by using an effective stress analysis. 2D numerical modeling was used in this study and the behavior of undrained soil was idealized using a cocktail glass model. The numerical results were compared with experimental results from a 1-G shaking table test with a scale of 1:60. The results indicate that the settlement of surface ground and SPSP foundation rapidly increase when the liquefaction occurs and is significantly influenced by permeability coefficient of ground.

Analysis of Strain-gage Records from a Static Loading Test on a CFA Pile

A static test was performed on a 610-mm diameter, 10 m long CFA pile installed through 3 m of clay and sand and into a thick deposit of lacustrine clay. The loading procedure included prolonged load-holding and an unloading-reloading event, which adversely affected the interpretations of the strain records and demonstrated the inadvisability of not performing a test with equal load-increments and equal load-holding durations and avoiding all unloading-reloading sequences. The pile was strain-gage instrumented at three levels and the recorded strains were used to calculate the pile axial stiffness and determine the load distributions for the applied load. Back-calculations using effective stress analysis were fitted to strain-gage determined load distributions and were then used in simulating the measured pile-head load-movement of the test pile.